The idea that vision is an active process has recently attracted considerable interest. Nowhere is the active nature of perception more evident than in the construction of a stable image of the world. As we move our eyes, new images are constantly presented to the brain yet we perceive the world as staying still. The perception stability we experience is thought to depend on a convergence of visual signals and corollary discharges reflecting the generation of voluntary eye movements. The goal of these experiments is to understand the impact of motor action on sensory processing as it relates to spatial constancy. We will ask how a specific motor act, saccadic eye movement, affects the representation of visual stimuli in primate cortex. Neurons in monkey parietal cortex have been shown to remap the presentation of a visual stimulus when the eyes move. This surprising observation has raised numerous questions about the neural mechanism underlying spatial constancy. The proposed experiments are designed to characterize the impact of the behavioral relevance of the stimulus on remapping (Aim 1); to discovered whether similar phenomena occur at earlier stages of the visual hierarchy (Aim 2); to determine how visual information is remapped from one hemisphere to the other (Aim 3); and to explore the interactions among frontal and parietal cortical stages which may underlie the process of updating spatial representations (Aim 4). Findings from these studies will provide a deeper understanding of the natural of spatial representation in cortex. Such an understanding is necessary as a step towards designing scientifically based diagnostics and rehabilitation programs for patients who have impair spatial functioning as a result of parietal lobe damage.